Passive, or keyless, entry systems in vehicles are gaining in popularity. In previous systems, there was a one-to-one communication that took place between the vehicle and the keyless entry device, i.e., the fob. In present passive entry systems, there is a “handshake” operation that must take place between the fob and the vehicle in order to unlock the vehicle. An issue arises, however, when multiple fobs are configured to passively unlock a vehicle, as the vehicle can only communicate with one fob at a time. Further, the complexity of this issue becomes more glaring when multiple fobs are to be configured to interface with a fleet of vehicles.
One typical solution for passive entry is to marry a fob to the fleet of vehicles and to have the fob talk during a predetermined time slot. In these systems, the number of fobs that can be used is limited by the number of time slots in a transmission period, e.g., up to 8 time slots. The only way to increase the number of fobs in the fleet is to increase the transmission period. Consumers, however, are accustomed to the keyless entry working in less than a second. Therefore, increasing the transmission period and the amount of time slots in order to increase the amount of fobs that can unlock a fleet of vehicles is not a desirable solution.
Another drawback with the current passive entry solutions is that marrying fobs to a fleet of vehicles does not allow new cars to be added to the fleet without having to configure the vehicle to work with the old fobs or issuing new fobs for the new vehicles. This is problematic in the police vehicle fleets or taxi service fleets, where new vehicles can be added to the fleet every year.
Thus, there is a need for an efficient system for enabling a plurality of fobs to passively unlock and lock a fleet of vehicles without having to marry the fobs to the fleet of vehicles.